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From:   Daniel Bristot de Oliveira <bristot@kernel.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Daniel Bristot de Oliveira <bristot@kernel.org>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Jonathan Corbet <corbet@lwn.net>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Marco Elver <elver@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Gabriele Paoloni <gpaoloni@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Clark Williams <williams@redhat.com>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-trace-devel@vger.kernel.org
Subject: [PATCH V4 10/20] rv/monitor: Add the wwnr monitor skeleton created by dot2k
Date:   Thu, 16 Jun 2022 10:44:52 +0200
Message-Id: <7d1b2238aa5c805501ae3dc80b213d06f6588cb3.1655368610.git.bristot@kernel.org>
In-Reply-To: <cover.1655368610.git.bristot@kernel.org>
References: <cover.1655368610.git.bristot@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Per task wakeup while not running (wwnr) monitor, generated by dot2k
with this command line:

  $ dot2k -d wwnr.dot -t per_task

The model is:
 ----- %< -----
digraph state_automaton {
	center = true;
	size = "7,11";
	{node [shape = plaintext, style=invis, label=""] "__init_not_running"};
	{node [shape = ellipse] "not_running"};
	{node [shape = plaintext] "not_running"};
	{node [shape = plaintext] "running"};
	"__init_not_running" -> "not_running";
	"not_running" [label = "not_running", color = green3];
	"not_running" -> "not_running" [ label = "wakeup" ];
	"not_running" -> "running" [ label = "switch_in" ];
	"running" [label = "running"];
	"running" -> "not_running" [ label = "switch_out" ];
	{ rank = min ;
		"__init_not_running";
		"not_running";
	}
}
 ----- >% -----

This model is broken, the reason is that a task can be running in the
processor without being set as RUNNABLE. Think about a task about to
sleep:

1:	set_current_state(TASK_UNINTERRUPTIBLE);
2:	schedule();

And then imagine an IRQ happening in between the lines one and two,
waking the task up. BOOM, the wakeup will happen while the task is
running.

Q: Why do we need this model, so?
A: To test the reactors.

Cc: Wim Van Sebroeck <wim@linux-watchdog.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Gabriele Paoloni <gpaoloni@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-trace-devel@vger.kernel.org
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
---
 kernel/trace/rv/monitors/wwnr/wwnr.c | 115 +++++++++++++++++++++++++++
 kernel/trace/rv/monitors/wwnr/wwnr.h |  38 +++++++++
 2 files changed, 153 insertions(+)
 create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.c
 create mode 100644 kernel/trace/rv/monitors/wwnr/wwnr.h

diff --git a/kernel/trace/rv/monitors/wwnr/wwnr.c b/kernel/trace/rv/monitors/wwnr/wwnr.c
new file mode 100644
index 000000000000..8ba01f0f0df8
--- /dev/null
+++ b/kernel/trace/rv/monitors/wwnr/wwnr.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/ftrace.h>
+#include <linux/tracepoint.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/rv.h>
+#include <rv/instrumentation.h>
+#include <rv/da_monitor.h>
+
+#define MODULE_NAME "wwnr"
+
+/*
+ * XXX: include required tracepoint headers, e.g.,
+ * #include <linux/trace/events/sched.h>
+ */
+#include <trace/events/rv.h>
+
+/*
+ * This is the self-generated part of the monitor. Generally, there is no need
+ * to touch this section.
+ */
+#include "wwnr.h"
+
+/*
+ * Declare the deterministic automata monitor.
+ *
+ * The rv monitor reference is needed for the monitor declaration.
+ */
+struct rv_monitor rv_wwnr;
+DECLARE_DA_MON_PER_TASK(wwnr, char);
+
+/*
+ * This is the instrumentation part of the monitor.
+ *
+ * This is the section where manual work is required. Here the kernel events
+ * are translated into model's event.
+ *
+ */
+static void handle_switch_in(void *data, /* XXX: fill header */)
+{
+	struct task_struct *p = /* XXX: how do I get p? */;
+	da_handle_event_wwnr(p, switch_in_wwnr);
+}
+
+static void handle_switch_out(void *data, /* XXX: fill header */)
+{
+	struct task_struct *p = /* XXX: how do I get p? */;
+	da_handle_event_wwnr(p, switch_out_wwnr);
+}
+
+static void handle_wakeup(void *data, /* XXX: fill header */)
+{
+	struct task_struct *p = /* XXX: how do I get p? */;
+	da_handle_event_wwnr(p, wakeup_wwnr);
+}
+
+static int start_wwnr(void)
+{
+	int retval;
+
+	retval = da_monitor_init_wwnr();
+	if (retval)
+		return retval;
+
+	rv_attach_trace_probe("wwnr", /* XXX: tracepoint */, handle_switch_in);
+	rv_attach_trace_probe("wwnr", /* XXX: tracepoint */, handle_switch_out);
+	rv_attach_trace_probe("wwnr", /* XXX: tracepoint */, handle_wakeup);
+
+	return 0;
+}
+
+static void stop_wwnr(void)
+{
+	rv_wwnr.enabled = 0;
+
+	rv_detach_trace_probe("wwnr", /* XXX: tracepoint */, handle_switch_in);
+	rv_detach_trace_probe("wwnr", /* XXX: tracepoint */, handle_switch_out);
+	rv_detach_trace_probe("wwnr", /* XXX: tracepoint */, handle_wakeup);
+
+	da_monitor_destroy_wwnr();
+}
+
+/*
+ * This is the monitor register section.
+ */
+struct rv_monitor rv_wwnr = {
+	.name = "wwnr",
+	.description = "auto-generated wwnr",
+	.start = start_wwnr,
+	.stop = stop_wwnr,
+	.reset = da_monitor_reset_all_wwnr,
+	.enabled = 0,
+};
+
+int register_wwnr(void)
+{
+	rv_register_monitor(&rv_wwnr);
+	return 0;
+}
+
+void unregister_wwnr(void)
+{
+	if (rv_wwnr.enabled)
+		stop_wwnr();
+
+	rv_unregister_monitor(&rv_wwnr);
+}
+
+module_init(register_wwnr);
+module_exit(unregister_wwnr);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("dot2k: auto-generated");
+MODULE_DESCRIPTION("wwnr");
diff --git a/kernel/trace/rv/monitors/wwnr/wwnr.h b/kernel/trace/rv/monitors/wwnr/wwnr.h
new file mode 100644
index 000000000000..f3dc160642bf
--- /dev/null
+++ b/kernel/trace/rv/monitors/wwnr/wwnr.h
@@ -0,0 +1,38 @@
+enum states_wwnr {
+	not_running_wwnr = 0,
+	running_wwnr,
+	state_max_wwnr
+};
+
+enum events_wwnr {
+	switch_in_wwnr = 0,
+	switch_out_wwnr,
+	wakeup_wwnr,
+	event_max_wwnr
+};
+
+struct automaton_wwnr {
+	char *state_names[state_max_wwnr];
+	char *event_names[event_max_wwnr];
+	char function[state_max_wwnr][event_max_wwnr];
+	char initial_state;
+	char final_states[state_max_wwnr];
+};
+
+struct automaton_wwnr automaton_wwnr = {
+	.state_names = {
+		"not_running",
+		"running"
+	},
+	.event_names = {
+		"switch_in",
+		"switch_out",
+		"wakeup"
+	},
+	.function = {
+		{     running_wwnr,               -1, not_running_wwnr },
+		{               -1, not_running_wwnr,               -1 },
+	},
+	.initial_state = not_running_wwnr,
+	.final_states = { 1, 0 },
+};
-- 
2.35.1